Version 0.11.0 adds support for Templated Responses! A library of templates can be configured in the Templates tab of the app's Preferences. These templated replies can be inserted in the compose window either by clicking the Template toolbar icon, or by using the ⌘/ keyboard shortcut.

Some rudimentary variable substitution is supported: for example, to insert the first name of a recipient, include the following pattern in your template:

Hi {{ recipient.first_name | 'Friend' }}

(where the 'Friend' is a required fallback name if there is no recipient specified yet). Please let us know what other variables you'd like to see supported!

Unfortunately, the Gmail API does not expose Gmail's internal templates feature, so templates you've created in Mimestream do not sync with Gmail (and vice versa). If you haven't already, please star the Gmail API issue at: https://issuetracker.google.com/issues/174678306 in order to help express your desire for this functionality to Google. If the Gmail API added this capability, Mimestream would be able to then sync with Gmail.